This invention relates to distributed control of fluid flow paths in contexts in which the flow paths, the equipments coupled to the flow paths, or both may fail or be damaged.
Seagoing vessels, regardless of whether they are intended for sport, commerce, or warfare, share in common the need to maintain their buoyancy and control in the face of potentially violent conditions including storms, grounding, andor hostile action. Maintaining control and buoyancy in the face of damage due to such violent conditions may require rapid amelioration of, or adaptation to, such damage. In a large ship, there may be many compartments, the entrances to which are separated by a sufficient distance from each other so that considerable time may be required for movement from one compartment to another. The existence of such compartments has in the past given rise to the need for an observer assigned to each compartment or set of compartments to monitor conditions. It might be thought that speaker tubes or telephones would be suitable for communicating between each of the various compartments and a control center or bridge, but there is a real possibility that damage to a compartment might also damage the communications equipment. Consequently, warships assign crew members to be messengers, whose duty is to carry information from the compartments to the control center or bridge in the event of a break in the communications. Since damage to one compartment of a ship may require adjustments, in many compartments, as for example when flooding of a compartment requires redistribution of the ship""s load or supplies to prevent excessive list. The adjustments may include operation of valves and switches within the compartments, as might be required, for example, to start pumps and open valves for the dumping overboard of bilge water, or for redistributing liquid fuel from tanks on one side of the ship to tanks on the other side. Because time is very important when attempting to cope with damage, warships have in the past stationed crews at various locations about the ship. These crews are charged with the duties of operating valves and switches as commanded or trained. In addition to such adjustments, additional crews must be provided to be on standby for firefighting, for damage repair, and for tending the injured. In the case of a warship, a portion of the crew must additionally be used for manning weapons and countermeasure. Since the tending of injured presupposes that some of the crew is not capable of performing its duties, the crew must, even when reduced in number by casualties, be large enough to be able to perform all of the tasks associated with tending a ship in distress. All of these considerations result in the manning of ships with crews large enough to provide xe2x80x9csurgexe2x80x9d capability for the handling of any emergency. A large battleship of WWII vintage had a crew in excess of 3000 men, and an aircraft carrier in the vicinity of 5000. Even modern missile destroyers require crews exceeding 300.
The presence of such large crews inevitably has its effects on ship design. It will be clear that the housekeeping and support requirements tend to expand disproportionally as the crew grows larger. The ship itself must be large in order to hold the oversize crew, and must carry additional stores such as food, which makes it larger still. Food preparation areas must be larger with a large crew, and the additional food preparation personnel in turn require their own support staff and ship facilities. The cost of ships is adversely affected by the need for a crew of a size to provide surge capability, and the cost of operating such ships is directly increased by the supernumerary members of the crew. The operating cost is further increased by the need to maintain the supernumerary members. It is thus of great importance in ship design to take into account the staffing requirements of the ship, and to improve ship design in such a manner as to minimize the crew size.
A part of the invention is based, in part, on the realization that automation can fulfil some of the tasks now performed by supernumerary crew members.
A circulating fluid system according to an aspect of the invention tends to cause fluid flow through at least one fluid-using or fluid-affecting device, such as a heat exchanger of a set of heat exchangers in the described examples. In such a system, any heat exchanger of the set may fail. The system includes a plurality of heat exchangers, each including a first port and a second port connected by a path for the flow of the fluid between the first and second ports. A first fluid path extends from a first fluid bifurcation to the first port of a first heat exchanger of the set of heat exchangers. The first fluid path includes a first software-controllable valve and a first flow sensor. The system also includes a second fluid path extending from the first bifurcation to the first port of a second heat exchanger of the set of heat exchangers. The second fluid path includes a second software-controllable valve and a second flow sensor. The system also includes a third fluid path extending from the first port of the first heat exchanger to the first port of the second heat exchanger. The third fluid path includes a third software-controllable valve and a third flow sensor. A fluid sink is coupled to a second bifurcation. A fourth flow sensor lies in a fourth fluid flow path extending from the second port of the first heat exchanger to the second bifurcation. A fifth flow sensor lies in a fifth fluid flow path extending from the second port of the second heat exchanger to the second bifurcation. A sixth fluid flow path couples the first bifurcation to a source of pressurized fluid. A communication network interconnects the flow meters and valves for providing a path for the flow of information relating to the state of each valve and the flow rate sensed by each flow sensor. An independent first program (which may be either firmware or software) is associated with the first valve. The first program is preloaded with information about the third and fourth fluid flow paths, for receiving from the network current fluid flow information associated with at least the third and fourth flow sensors, for, in at least one mode of operation, summing the flows associated with the third and fourth fluid flow paths to thereby form a first summed fluid flow, and for comparing the first summed fluid flow with the flow through the first flow sensor, and for closing the first valve, for thereby closing off the first fluid flow path when the first summed flow is not equal to the flow through the first flow sensor. An independent second software program is associated with the second valve. The second software program is preloaded with information about the third and fifth fluid flow paths, for receiving from the network current fluid flow information associated with at least the third and fifth flow sensors, for summing the flows associated with the third and fifth flow paths to form a second summed fluid flow, and for comparing the second summed fluid flow with the flow through the second flow sensor, and for closing the second valve for closing off the second flow path when the second summed flow is not equal to the flow through the second flow sensor.